Bought the air card this spring in Florida...only got to use it for 10 days b4 heading north...love it!...way more convenient than hunting for a wifi spot...and for us Canadians, we don't have to buy a contract that would be a waste of money for the time we are home and can't access a US signal. It uses the sprint network, you only buy the amount of download bytes you need...a $10 card lasted 10 days and I did not exhaust all the allotted internet "space" on the card. I'm a convert! Thank you, Sir Richard Branson
Al & Inge in the Road Toad

Some phones, like the Nokia E71 for example with JoikuSpot installed (free) will produce a wifi cloud that you can tether your wifi enabled device to...anywhere you can get a cell signal. The application is not limited to Nokia but you do need a 3g capable phone.